Incubation temperature influences the behavioral traits of a young precocial bird

Abstract

The environment in which animals develop can have important consequences for their phenotype. In reptiles, incubation temperature is a critical aspect of the early developmental environment. Incubation temperature influences morphology, physiology, and behavior of non-avian reptiles, however, little is known about how incubation temperature influences offspring phenotype and behaviors important to avian survival. To investigate whether incubation temperature influences avian behaviors, we collected wood duck (Aix sponsa) eggs from the field and incubated them at three naturally occurring incubation temperatures (35.0, 35.8, and 37.0°C). We conducted multiple repeated behavioral trials on individual ducklings between 5 and 15 days post-hatch to assess activity, exploratory, and boldness behaviors, classified along a proactive-reactive continuum. We measured growth rates and circulating levels of baseline and stress-induced corticosterone levels to investigate possible physiological correlates of behavior. Ducklings incubated at the lowest temperature displayed more proactive behaviors than those incubated at the two higher temperatures. We also found that younger ducklings exhibited more proactive behavior than older ducklings and males exhibited more proactive behavior than females. Further, duckling behaviors were repeatable across time and contexts, indicative of a proactive-reactive continuum of behavioral tendencies. However, neither corticosterone levels nor growth rates were related to behavior. This provides some of the first evidence that incubation temperature, a critical parental effect, influences avian offspring behaviors that may be important for survival. Our results identify incubation temperature as a mechanism that contributes to the development of behavioral traits and, in part, explains how multiple behavioral types may be maintained within populations.

Postnatal care generates phenotypic behavioural correlations in the Japanese quail

“…This result more broadly confirms that the absence of informative cues in impoverished environments result in reduced phenotypic constraints and more unpredictable responses. The current study focused on behavioural correlations of offspring at the age when they disperse, and when their behavioural responses are crucial for their survival (Hope et al 2018). Further work is required to determine how early life factors such as maternal deprivation affect behavioural correlations across the lifespan, as such correlations can change during later ontogenetic stages (e.g.…”

“…Accordingly, two studies in artificially reared precocial birds reported an absence of correlation between glucocorticoid levels, mass, and behaviour (e.g. Mignon-Grasteau et al 2003;Hope et al 2018). Adoption had a stronger effect on behavioural correlations in males.…”

Applications of machine learning in behavioral ecology: Quantifying avian incubation behavior and nest conditions in relation to environmental temperature

“…Additionally, it is increasingly apparent that the effects of incubation temperature do not end upon hatching. In both precocial and altricial species, incubation temperature affects a suite of post-hatching traits critical to fitness of young birds (e.g., [16][17][18][19][20][21]), as well as secondary sex ratios [22,23]. These findings suggest that incubation temperature plays an important role in ecological and evolutionary processes in birds and should be an important factor considered in avian conservation efforts [10,15,17,24].…”

Introduction to the special issue—Developmental plasticity in reptiles: Physiological mechanisms and ecological consequences

“…Complementary to this review, Bowden and Paitz (2018) discussed the importance of integrating natural conditions into laboratory experiments (e.g., fluctuating temperature and natural variation in yolk estrogens) that examine TSD. The third and fourth papers in this theme describe original research that quantifies the potential role of incubation temperature in shaping sexual size dimorphism in geckos (Kratochvíl, Kubicǩa, Vohralík, & Starostová, 2018) and behavioral traits in birds (Hope, Kennamer, Moore, & Hopkins, 2018). Several other papers in this issue examine the phenotypic consequences of incubation temperature, but address this topic from a mechanistic perspective or in the context of maternal effects and global change (see below).…”